Here is the full list of all 18 M.A.R.S.S. achievements.
Amazing, you have discovered how to open Doors
Capture the capitalist flag on the tutorial level
Learn the abilities of C.O.M.R.A.D.E. Combat
Learn the abilities of C.O.M.R.A.D.E. Overload
You have successfuly destroyed the Final Boss
Complete all the levels, including the Special Levels
At any point of the game have more than 30 active comrades
At any point of the game lose all your active comrades
Eliminate 10 enemies with electric damage
Eliminate 5 enemies with fire damage
Use an artillery attack to destroy a crate or a rock
Make Ball Enemy destroy a crate or a rock
Kill an enemy with the damage of a mine
Pick 100 cpus
Spawn 80 Comrades
Kill 20 Enemies
Complete the Special Level A-2, this level can be unlocked after completing level 8
Complete the Special Level Escape, this level can be unlocked after completing level 13